Asexual propagation of plants has been shown for some species to yield large numbers of genetically identical embryos, each having a capacity to develop into a normal plant. Such embryos are usually further cultured under laboratory conditions until they reach an autotrophic “seedling” state characterized by an ability to produce its own food via photosynthesis, resist desiccation, produce roots able to penetrate soil, and fend off soil microorganisms. Some researchers have experimented with the production of artificial seeds, known as manufactured seeds, in which individual plant somatic or zygotic embryos are encapsulated in a seed coat. Examples of such manufactured seeds are disclosed in U.S. Pat. No. 5,701,699, issued to Carlson et al., the disclosure of which is hereby expressly incorporated by reference.
Typical manufactured seeds include a seed shell, synthetic gametophyte and a plant embryo. A manufactured seed that does not include the plant embryo is known in the art as a “seed blank.” The seed blank typically is a cylindrical capsule having a closed end and an open end. The closed end is typically sealed by crimping an end of the seed blank to create a dead end seal along a single axis of the seed blank. Thereafter, synthetic gametophyte is inserted into the seed shell and an embryo is sealed within the seed shell by a live end seal.
In the past and as noted above, the dead end seal is formed by crimping an end of the seed shell to close one end of the seed blank. Although such types of dead end seals are successful in closing one end of the seed blank, they are not without their problems. As a non-limiting example, such dead end seals define a seal area that is wider than the outside diameter of the seed blank itself. This creates a need for an oversized guide way when automatically transporting the seed. Further, such dead end seals have a sharp edge that catches and snags on any non-continuous surface. Finally, the flat seal surface acts as a wedge when in close proximity with other seeds to cause a binding effect that disrupts transportation of the seed during manufacture. Thus, there exists a need for an improved dead end seal for an artificial seed.